The role of a football manager is broadly comparable with the same role in the business world and as such she or he must take full responsibility when things go wrong in the long term. The manager needs to pick the best team to win the game, in the knowledge that the players that make up the team are the right ones for their unique roles and are trained well and fully motivated for the task ahead.
A good manager will have excellent inter-personal skills and be able to communicate their ideas well to the players. They will make good decisions, at the appropriate time. This is especially true in soccer as it is in business. On the field of play, wise tactical decisions and good communication with the players will enable the team to effectively carry out the managers orders.
Much is often made of the expensive salaries that football players are on, with the negative assumption that if they are not performing well on the pitch, that they are overpaid and disinterested, and therefore responsible for a teams lack of success. While this may have some basis in truth at some times from a fans point of view, it does not tell the whole story.
A player must want to win and play well or why are they in the game? Players are always in the "shop window" and if they are demotivated then there must be an underlying reason. It may be a lack of fitness, tiredness or psychological. It may be caused by a bad professional attitude, but it is never irresolvable.
The manager must identify the reasons for under perfoming players and find solutions to it.
If it comes to making a tough decision, there are always other less well paid players with more to prove that the manager can draw upon. It is the managers responsibility to know when to drop the superstar players and for how long if this becomes necessary.
A case study could be made of Newcastle United. When Sir Bobby Robson was managing the team, they did not have the greatest players in the division, but they consistently punched above their weight. Players like Andy O'Brien and Titus Bramble in defence do not stand out as the greatest defenders, but Bobby Robson knew how to get the best out of the team. He also identified along with his scouting staff the right players to bring in to compliment the existing team and achieve the right balance. While Newcastle did not win any trophies in his time, they did finish in the top 3 or 4 in the English Premier league, qualifying for the European Champions League and even beat the mighty Barcelona during his reign. Contrast that with his successor Graeme Souness, who brought in a lot of expensive players like Michael Owen but ended up at the wrong end of the table, battling relegation.
It is also the manager's job to identify the right players to bring in during the transfer window and as long as a manager has been given time to build their own team, then ultimately the buck stops with them. This requires good planning skills. If they do not achieve the potential or target that is expected of them then it is often time for the club to try a different manager. For each football club they may have a different target, and only the owner of the club can decide when the manager has failed in her or his mission. Even then, a soccer manager receives adequate compensation if they are released from their contract so it is not all bad in that eventuality.